76 research outputs found
A 1.1 to 1.9 GHz SETI Survey of the Kepler Field: I. A Search for Narrow-band Emission from Select Targets
We present a targeted search for narrow-band (< 5 Hz) drifting sinusoidal
radio emission from 86 stars in the Kepler field hosting confirmed or candidate
exoplanets. Radio emission less than 5 Hz in spectral extent is currently known
to only arise from artificial sources. The stars searched were chosen based on
the properties of their putative exoplanets, including stars hosting candidates
with 380 K > T_eq > 230 K, stars with 5 or more detected candidates or stars
with a super-Earth (R_p 50 day orbit. Baseband voltage data
across the entire band between 1.1 and 1.9 GHz were recorded at the Robert C.
Byrd Green Bank Telescope between Feb--Apr 2011 and subsequently searched
offline. No signals of extraterrestrial origin were found. We estimate that
fewer than ~1% of transiting exoplanet systems host technological civilizations
that are radio loud in narrow-band emission between 1-2 GHz at an equivalent
isotropically radiated power (EIRP) of ~1.5 x 10^21 erg s^-1, approximately
eight times the peak EIRP of the Arecibo Planetary Radar, and we limit the the
number of 1-2 GHz narrow-band-radio-loud Kardashev type II civilizations in the
Milky Way to be < 10^-6 M_solar^-1. Here we describe our observations, data
reduction procedures and results.Comment: Accepted to the Astrophysical Journa
A Search for Extraterrestrial Technosignatures in Archival FAST Survey Data Using a New Procedure
The "search for extraterrestrial intelligence" (SETI) commensal surveys aim
to scan the sky to find possible technosignatures from the extraterrestrial
intelligence (ETI). The mitigation of radio frequency interference (RFI) is an
important step, especially for the most sensitive Five-hundred-meter Aperture
Spherical radio Telescope (FAST), which can detect more weak RFI. In this
paper, we propose several new techniques for RFI mitigation, and use our
procedure to search for ETI signals from the archival data of FAST's first SETI
commensal survey. We detect the persistent narrowband RFI by setting a
threshold of the signals' sky separation, and detect the drifting RFI (and
potentially other types of RFI) using the Hough transform. We also use the
clustering algorithms to remove more RFI and select candidates. The results of
our procedure are compared to the earlier work on the same FAST data. We find
that our methods, though relatively simpler in computation, remove more RFI
(99.9912% compared to 99.9063% in the earlier work), but preserve the simulated
ETI signals except those (5.1%) severely affected by the RFI. We also report
more interesting candidate signals, about a dozen of which are new candidates
that are not previously reported. In addition, we find that the proposed Hough
transform method, with suitable parameters, also has the potential to remove
the broadband RFI. We conclude that our methods can effectively remove the vast
majority of the RFI while preserving and finding the candidate signals that we
are interested in.Comment: 14 pages, 10 figures. AJ accepte
New SETI Sky Surveys for Radio Pulses
Berkeley conducts 7 SETI programs at IR, visible and radio wavelengths. Here
we review two of the newest efforts, Astropulse and Fly's Eye.
A variety of possible sources of microsecond to millisecond radio pulses have
been suggested in the last several decades, among them such exotic events as
evaporating primordial black holes, hyper-flares from neutron stars, emissions
from cosmic strings or perhaps extraterrestrial civilizations, but to-date few
searches have been conducted capable of detecting them.
We are carrying out two searches in hopes of finding and characterizing these
mu-s to ms time scale dispersed radio pulses. These two observing programs are
orthogonal in search space; the Allen Telescope Array's (ATA) "Fly's Eye"
experiment observes a 100 square degree field by pointing each 6m ATA antenna
in a different direction; by contrast, the Astropulse sky survey at Arecibo is
extremely sensitive but has 1/3,000 of the instantaneous sky coverage.
Astropulse's multibeam data is transferred via the internet to the computers of
millions of volunteers. These computers perform a coherent de-dispersion
analysis faster than the fastest available supercomputers and allow us to
resolve pulses as short as 400 ns. Overall, the Astropulse survey will be 30
times more sensitive than the best previous searches. Analysis of results from
Astropulse is at a very early stage.
The Fly's Eye was successfully installed at the ATA in December of 2007, and
to-date approximately 450 hours of observation has been performed. We have
detected three pulsars and six giant pulses from the Crab pulsar in our
diagnostic pointing data. We have not yet detected any other convincing bursts
of astronomical origin in our survey data. (Abridged)Comment: 9 pages, 6 figures, Accepted to Acta Astronautica "Special Issue:
Life Signatures
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